Liquid vs. Bar in Dr. Bronner’s Pure Castile Soap

The liquid came first – peppermint to be exact. Bar soap meandered in a few decades later. While there are hardliners in both camps, the difference between liquid and bar is mostly a matter of personal preference. However, there are some differences between the two.

Here are the ingredients side by side for the unscented Baby Mild castile soap. I chose our simplest soap, which lacks any essential oils, so that the differences are easier to see.

Comparison of Liquid vs. Bar Castile Soaps

Differences explained:

  • Liquid contains more water.
    • Why: There is just enough water in the liquid soaps to keep them liquid. Any less water and the soap begins to solidify. To test this, leave the cap off your bottle for a day, and you’ll notice the soap’s starting to gel. You can reliquify it with a bit of water. (The thickness, or thinness, of the soap is not due to high water content, but to the consistency of the various oils.)
    • Effect on Performance: None
  • Liquid uses potassium hydroxide to saponify oils; bar uses sodium hydroxide.
    • Why: Hardness – sodium hydroxide produces a harder soap than potassium hydroxide. The purpose of these strong alkalis is to blast apart the oil molecules, separating the glycerin from the fatty acids. The fatty acids then reattach to the sodium or potassium ion, leaving the glycerin and water (hydroxide) free-floating. (Just a sidenote – soap cannot be made any other way. None of these alkalis are left in the soap. Check out the link at the bottom about soapmaking.)
    • Effect on Performance: None
  • Bar contains palm oil, in addition to coconut oil.
    • Why: Palm oil hardens more than coconut oil. Coconut oil, even in its solid state, is mushy, and it melts at 76° F.
    • Effect on Performance: Bar soap is slightly more moisturizing. Palm oil contains stearic acid, which some people find to be less drying than the lauric acid found in coconut oils.
  • Bar contains salt (NaCl – sodium chloride or table salt).
    • Why: Also serves as a hardener.
    • Effect on Performance: Bar soap is slightly more moisturizing. Since our bodies are slightly salty, salt water is gentler on our skin than pure water. Salty soap is, too.

Other Differences in Formulation:

  • How the Hemp and Jojoba oils are added:
    • In the liquid soaps, the hemp and jojoba oils are saponified, i.e. turned into soap, along with the coconut and olive oils. However, in the bar soaps, these two oils are added unaltered after the saponification process. This is called “superfatting” the soaps. A while back my brothers tried superfatting the liquids with the hemp and jojoba oils, but found that the oils separated out and floated to the top.
    • Effect on Performance: Bar soaps produce a creamier lather and are slightly more moisturizing.
  • Amount of Essential oils:
    • This is only relevant to the scented soaps (everything except the unscented Baby Mild). The liquid soaps have a higher percentage of the essential oils than do the bar soaps. Once again, the issue at stake is hardness. The bar soaps would soften with that high a concentration of the essential oils.
    • Effect on Performance: This is entirely a matter of personal preference. Those who like an intense whiff of scent, and those who are looking for the specific benefits of the particular essential oils, should opt for the liquids. Those who like a little scent, but not too much, the bar soap would be better.

Differences in usage:
For all body applications, they are entirely interchangeable – from washing face, hair, or body, or shaving. For around the house purposes, you would need to take the extra step of dissolving the bar soaps in water before using them in a spray bottle solution, but they are equally effective. Also, the bar soap can be grated to achieve a kind of powdered soap for laundry, although the liquid works just as well.

Volume of actual soap:
I don’t know how to de-math this, but people who put together their own recipes for cleaners might want to know this. Bar soaps are 5% water; liquids are 61%. The chemistry is a little different for both, but considering that a bar of soap weighs 5 oz, and thus 4.75 oz of it is soap, you would need 12.18 ounces (a little over 1 ½ c.) of liquid soap to equal the soap content of a 5 oz bar. Doing the math the other way, 1 cup of liquid soap equals approximately 2/3 of a bar (or 3.64 oz.) of Dr. B’s bar soap.

Bottom Line:
The Dr. Bronner’s Bar and Liquid Pure Castile soaps are interchangeable. However, the bars are slightly more moisturizing. The liquids are slightly more scented.

If you want more info on the process of soapmaking, check out this article:

If you have any other questions about what is in the soap and why or where it is sourced and why or anything else, let me know!

131 thoughts on “Liquid vs. Bar in Dr. Bronner’s Pure Castile Soap

  1. Can you recommend a type of dispenser for Castile oil when used in shower? As you discussed in the past it does clog and spews liquid out on its own. Someone mentioned dish detergent dispenser. Thank you

  2. Hi Zen – There is no sodium hydroxide in the Dr. Bronner’s soap that you’re buying. The NaOH molecule is completely split apart and it’s parts reattach to other molecules, forming completely different substances: soap (scientifically called sodium cocoate) and water. You can read more about the chemistry behind it here: Let me know if I can be of further help!

    Hi Larry – Most of our soaps are either induction sealed or pressure sealed. Only the 2 oz and 4 oz bottles are not.

    Hi Erin – The only dispenser that works is a foaming pump dispenser. Dilute the soap at a 1:5 ratio with water for that. I do not recommend the dish detergent dispenser.

    All the best,

  3. Lisa, Thank you for your work on this blog. I’ve used Dr. Bronner’s for years and enjoy the soaps a lot. But they are a little more expensive than other options, and lately I’ve become a more frugal about such things, so I’ve been trying to figure out the most cost-efficient way of using it. (I just use it in the shower, not around the house.) I noticed with interest your comment that the soap content in a 5 oz. bar equals the soap content in 12.18 oz. of the liquid soap. But it seemed like your calculation was assuming an equivalence between the bar’s “ounces” (measuring weight) and the liquid’s “ounces” (measuring volume). But those two kinds of “ounces” aren’t usually equivalent, are they? I trust you know what you’re talking about, but would mind explaining why the volume/weight distinction isn’t affecting your calculation?

  4. Hi Kirk – I absolutely love having occasion to draw on those high school chemistry classes now that I am an adult! (I am totally serious. I’m a bit of a nerd.) So! As you astutely pointed out, in our totally convoluted system of weights and measures in America, we use the same word “ounce” for a liquid measurement (equaling 2 Tablespoons) and a dry measurement (equaling 1/16 of a pound). The correlation between the two is that at sea level, one liquid ounce of water also equals 1/16 of a pound. However, anything with a density different from water will have a different liquid measurement from dry. Stick with me here – I’m getting somewhere. Now, I do not know the exact density of Dr. Bronner’s castile soap. It is a blend of ingredients, but is mostly made up of oils. I’ll go with the density of olive and coconut oils because those are the main ingredients. Both of these oils are slightly less dense than water, but at the amounts we’re referring to in these recipe conversions, they would easily round up to 1 liquid ounce oil = 1 weight ounce oil.

    That means, that for most household purposes, in comparing the soap quantity in Dr. Bronner’s bar to the soap quantity in Dr. Bronner’s liquid, you can pay little attention to liquid vs. dry ounces.

    If you are planning some sort of large scale project, where the slight difference between the liquid vs. dry would be multiplied, please let me know and I will be happy to do a more exact calculation for you.

    Thanks for asking!

    All the best,

  5. Thank you so much for your prompt reply and explanation. Good to know our system of measurements isn’t completely arbitrary!

    Anyhow, based on your conversion formula, an ounce of undiluted soap costs about 30% more if bought as a liquid instead of in a bar (or more, if you buy the liquid in smaller bottles). That would predispose me to buying the bar soap… except that my anecdotal experience is that I go through the bars much more quickly than the liquid. That seems counter-intuitive since the bars have a higher concentration of soap. Is that something you’ve encountered? Do you have any idea why the bars go faster? I wonder if it’s because I don’t use a wash cloth?

  6. I just discovered your blog. Awesome explanations. Is it OK to use the bar soap as a face cleaner? I make my own coconut oil cleanser at night, but was looking for a bar soap for my morning showers to use on my face.
    Thank you.

  7. @Flo:
    I use the baby mild bar soap on my face, hair and body every day. At first I developed some small dry patches on my face but I used coconut oil as a moisurizer before showering and soon the dry patches went away. I believe it was my skin adjusting to the new soap. I also make my own sugar scrub with coconut oil, cocoa butter and turbinado sugar and I use that to exfoliate my face once a week, before showering, and then I wash my face with the bar soap. The result is very soft but not greasy skin.

  8. I’ve been using the Tea Tree scent for my hair and my acne-prone skin and it’s been working great! It’s so awesome to find a pure product that I can use to wash my hair, face, body, and veggies, too. The soap’s brought out my hair’s natural wave, which is great as it could sometimes be hidden by the chemicals in traditional shampoo. I didn’t use any rinses after the soap and it didn’t leave a greasy residue like I read could happen. Should I continue to use just the soap or would it be beneficial to use some sort of rinse afterwards?
    Love the blog and the product! Keep up the good work!

  9. I don’t really have a recipe but I think the last time I made a batch I used about 50-50 coconut oil and cocoa butter (melted in the microwave) and then I mix in the turbinado sugar until its the desired consistency. I have also added almond oil if the mixture is too thick; if the mixture is too hard at room temperature, melt it in the microwave and add more coconut or almond oil. I like sugar better than salt since salt can sting if you just shaved but I have made it with both. Salt works as a water softener and it leaves skin very soft so it can be used in place of the sugar if desired. Turbinado sugar can be too course for some people so you might also try regular white table sugar. You can use any combination of oils that you like and even add a drop or two of essential oils. I have made a salt scrub with lavender oil which is good to use before bedtime. Try making small batches till you find what you like. Be careful not to get any water into it or else the sugar and salt will dissolve.

  10. Thank you, Diane. I wonder how would be if I used coconut sugar. May have to try.

  11. LISA,

    I’ve read all the above and no one has really mentioned a much more serious matter (for those who have it) but my acne prone skin on my face.. struggled since i was 18 and I’m 23 now and it really stinks to see people eat crap day and night and never clean them selves or there bed sheets and there face is perfectly fine. but I’m over here like what the hell is life.. lol… :( ANYWAYS what is the best to use for my face?? I’ve used every stupid lying product on the market and did all the prescription stuff and all that is a lie and the government just wants my money and they get the doctors to lie. i tried the tea tree bar soap for a bit and it sort of worked a bit i guess but i think maybe my schedule of face washing might be the problem. a year ago i started washing my face and body at night with warm hot water then just rinsing off in cold water in the morning. seeing as washing my face with chemicals in the morning causes much more irritation in the skin since the sun is out. but i recently switch to the liquid version tea tree and its kind of made it worse. but it could just be getting used to it i suppose but once again i know there has to be a better schedule to use this stuff on my face like with certain water temperatures or times of the day and following up on it etc. i know these are questions for a “dermatologist” but that is bull crap I’m sorry I’ve been to a few and they all say different things so to me there all full of crap. :( wish big brother scientist governments would just release to the people the real cure for acne cause they obviously have it. but anyway sorry for kind of ranting i would appreciate your reply.. thank you much and i greatly appreciate it.

  12. It’s too bad that neither is Castille soap as: “Castile Soap or as it’s originally named in Spain Jabón de Castilla, is made exclusively with unrefined Extra Virgin Olive Oil. Unfortunately, pseudo called Castile Soaps that contain little or non Olive Oil in their formulations are widely available in today’s market. If it’s not made with 100% Olive Oil is NOT TRUE Castile Soap.”

    I see your bars in Trader Joes, shake my head and laugh as I walk away. Please stop calling this Castille Soap. Your ingredients are great but know what you are labeling first please.

  13. Lisa,

    I love your various blog topics. They are so informative.

    I am starting to recycle laundry water – I just set up a passive system and recycled my first load to water my plants. Perhaps later I will also reuse shower water. I want to reduce the amount of salt and other chemicals that I add to the soil. I am researching the best cleaners to use on laundry, house, and personal cleaning. How much salt is in Sal Suds and Castile bar soap?

    With grey water re-use in mind, how should I use Sal Suds or Liquid Castile for laundry? Borax is a no no for plant re-use so I won’t be using that. I suppose I also have to think about the pH of the grey water, don’t you think? It all seems to get so complicated when the water doesn’t disappear down a hole.

    And what about your hair rinse? Chemical composition. Grey water re-use friendly?

    Thanks so much.

  14. I amused to using a moisturizer after washing my face but now that I am switching to this all natural remedy, I don’t want to use my formal moisturizer. I have acne prone skin, any suggestions?

  15. Hi, I am interested in knowing how can we turn the bar soap into liquid soap. It is insanely expensive to buy Dr Bronner here in Singapore. 2 FL OZ actually cost S$4.90!

  16. I have a question! I prefer the bar soap, however all of the different recipes I have call for a certain amount of liquid. I can’t use the liquid in these recipes, because it makes me itch (even the baby mild!)….. I am hoping that you can help me figure out how to dilute the bar soap with water (or however it should be done) so that I can use it in place of the liquid called for in all of the recipes….. Thank you so much!

  17. I have a recipe for laundry soap and it calls for a bar of fels-naptha dissolved into 4 cups of water. How would I substiute liquid dr. Bronners soap into this recipe? Thank you for any help.

  18. Good morning. I am stuck with about ten loads of laundry to do, and the only soap I have is for the body, though I have Tea Tree, baby, and almond . I thought I still had Sal Suds but apparently not. Can I use any of these in the washer? Thx.

  19. hi.
    so I have been on no-poo for 60 days.
    I have washed with egg, green tea, coffee, yoghurt. nothing works amazingly. still trying here!
    so my no-poo is basically, I can use anything on my hair which is natural.
    The hydroxide. is the only worry to me, but there is none left by the time the product is made? is this the ‘lye’?
    would you say I am safe to use your soaps as shampoo without breaking my 60 days!

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